The invention relates to a device for manufacturing parts which are provided with an outer profile wherein a work piece is pressed by a thrust piece in an advance direction through an annular cutting tool, the cutting tool has a plurality of cutting edges for removing material from the work piece, the cutting edges are progressively projecting in advance direction, each cutting edge removing material chips and the last cutting edge in advance direction corresponding to the desired outer profile of the part.
Such devices are for example known from U.S. Pat. Nos. 2,674,924, 2,547,509, 2,461,320, or DE-OS-2 259 120.
In these above mentioned devices of the prior art the cutting tool forms a closed pipe. Chip chambers for receiving the chips are formed between the cutting edges of this pipe. It makes difficulties to remove the chips out of the pipe. Thereby, the working cycle is prolonged in an undesirable way.
From DE-U-94 07 708.8 a device of the first-mentioned type is known in which the cutting tool has a plurality of annular discs which form the cutting edges and are spaced by spacers. Each of the spacers is formed by two rectangular plates laterally spaced, which form, therebetween, a channel communicating with the outside. Chips can be removed through this channel.
In this known arrangement the chips can be removed between each pair of the cutting edges only in two opposite radial directions. It has been found that also herein the chip removal makes difficulties.
It is the object of the invention to improve the chip removal in a device of the type mentioned in the beginning.
It is a further object of the invention to ensure, in a device of the type mentioned in the beginning, the secure holding of the work piece on the thrust piece. Particularly it should be possible to hold also small work pieces securely on the thrust piece and to machine them with a device of the type mentioned in the beginning.
Finally, it is an object of the invention, to manufacture parts of high dimensional accuracy and with high surface quality by means of a device of the type mentioned in the beginning.
An improvement of the chip removal is achieved by means of the device of the type mentioned in the beginning in forming chip chambers for receiving the chips between the cutting edges, which chip chambers are communicating with the outside through radial connecting openings distributed all around the circumference.
The chips are usually produced all around the circumference of the part. Due to the formation and arrangement of the connecting openings according to the invention, the chips can hence be distributed and radial removed all around the circumference where they are produced.
A secure holding of the work piece on the thrust piece of a device of the above mentioned type is ensured by a pressure pad extending through the cutting tool and supported on the side of the work piece opposite to the thrust piece, and by means for generating a contact force onto the pressure pad.
The working piece is then clamped between the thrust piece and the pressure pad. The force acting on the thrust piece and therethrough onto the work piece overcomes the force of the pressure pad. Thereby the pressure pad is pressed back by the cutting tool when the work piece is moving. By this clamping, also very small work pieces can be held securely and in defined location at the thrust piece.
To ensure a high-dimensional accuracy with the device of the firstly mentioned type, a calibrating tool having a passage is arranged behind the cutting tool as viewed in advance-direction, the dimensions of which tool at the rear outlet side correspond to the nominal dimensions of the part to be manufactured.
After the removing process performed by the cutting tool, thus a cold deformation takes place without separation of chips. Hereby the material is distributed and the surface polished. Thus parts with high dimensional accuracy and high surface quality can be produced.
The before mentioned characteristics of the invention are applied preferably in combination. They can be used also individually or in subcombinations.
Further modifications of the invention are subject matter of the subclaims.
An embodiment of the invention is further explained below referring to the accompanying drawings.